1. Field of the Invention
The invention relates to a white-light emitting semiconductor device, more particularly to a white-light emitting semiconductor device which has a superior color rendering index (CRI), and which is applicable to a car light, a camera flash, a luminescent device, and the like.
2. Description of the Related Art
A conventional fluorescent lamp contains rare earth phosphorescent coating. Therefore, the white light emitted by the conventional fluorescent lamp is primarily a light blend obtained via a spectrum combination of three primary color lights, i.e., blue light (wavelength: about 452 nm), green light (wavelength: about 543 nm), and red light (wavelength: about 611 nm). However, the light blend emitted by the conventional fluorescent lamp contains little of light, such as cyan light or yellow light, which has a spectrum between those of the primary color lights. Therefore, the conventional fluorescent lamp cannot provide a superior CRI.
Additionally, a mobile phone or a personal digital assistant having a digital camera function usually contains a white-light emitting device as a light source of the digital camera. The white-light emitting device usually contains a light emitting diode emitting blue light and a phosphorescent material excitable by the blue light to emit yellow light. The yellow light is combined with the blue light emitted by the light emitting diode to produce white light. For example, U.S. Pat. No. 5,998,925 discloses such a white-light emitting device. However, in the aforementioned white-light emitting device, since the intensity of the red light portion is insufficient, the CRI of the conventional white-light emitting device is inferior, which leads to an inferior image-capturing effect.